The character of Michael Myers was named after the
European distributor of Carpenter's previous film, Assault on
Precinct 13 as a kind of weird "thank you" for the film's
overseas success.

The original script, titled "The Babysitter Murders", had the events take place over
the space of several days. It was a budgetary decision to change the script to
have everything happen on the same day (doing this reduced the number of
costume changes and locations required) and it was decided that Halloween, the
scariest night of the year, was the perfect night for this to happen.

This was voted the fifth scariest
film of all time by Entertainment
Weekly.

As the movie was actually shot in early spring in southern
California (as opposed to Illinois in late October), the crew had to
buy paper leaves from a decorator and paint them in the desired
autumn colors, then scatter them in the filming locations.